[madghost]

I am looking to obtain a Philco Cathedral. I have seen a number of 70's and 90's for sale on E-Bay and elsewhere. Is the 90 that much of a better performer than the 70 that it is priced so much higher at auctions, etc? From what I have read, the 70 performs quite well and there isn't that much of a difference between the two except for two tubes.

Any insight would be helpful.

Thanks to all

[Terry Burns]

Hi Madghost,
There are some differences. Just glancing at the schematic the 70 volume control is in the antenna circuit. The 90 has its own 2nd detector and avc. The 70 looks to me that it doesn't. Also The volume is also controlled by changing the bias on the cathodes of two of the 24 tubes on the 70. The 90 also has two stages of audio amplification before the final output tube. The 70 uses the same tube as the 2nd detector and audio amplifaction.
I'm sure Ron and Chuck could tell you more. Both of my 90's play great. With a good antenna I pick up many stations across the dial. Sorry to say I have never listened a 70.

Hope this helps
Terry

[Chuck Schwark]

And there are three versions of the Mdoel 90, the origninal; Early, Mid and Late.

See the Early Cathedrals section of my site.

[Ron Ramirez]

Hi Madghost

The early 70 and early 90 (using two Type 45 output tubes) share the same front end, and neither have AVC.

The "mid" 90, the most common version with a single Type 47 output, uses AVC which makes a HUGE improvement in performance; i.e. no "blasting" as you tune across the dial, and less prone to fading.

The late 90 (push-pull 47 outputs) and late 70 both have autodyne converters, and both have AVC, so again their front ends are similar.

Both are good performers. To make a long story short, the 90 has extra amplification in its audio section. It is slightly larger than the 70. And there is just something special about it, I guess, that makes it more desirable.